1. Field of the Invention
The present invention relates to a data supplying apparatus and method for motion estimation, and more particularly, to an apparatus and method for supplying optimal data for a hierarchical motion estimator.
2. Description of the Related Art
Generally, image communications systems, such as a moving picture storage device of digital televisions, moving picture teleconferencing, or image telephones, send and receive large amounts of multimedia information including real-time moving pictures. The multimedia information in the image communications systems has become increasingly complicated, but communications networks for transmitting the information have not followed the changing complexity of the multimedia information. In particular, moving pictures constitute the largest percentage of the multimedia information, and thus require a compression technique. The basic idea of the compression technique is removing spacial and temporal redundancy in a video sequence. Motion compensated predictive coding is representative of a method of removing redundancy from the multimedia information.
In the motion compensated predictive coding, the motion of images viewed from a time axis can be estimated by searching for the positions of matching blocks between a previous frame (t-1) and a current frame (t). Conventional full and hierarchical searches have been proposed to for estimating motion. The full search requires a large number of calculations, and a memory (for example, a static random access memory (SRAM) or synchronous dynamic random access memory (SDRAM)) for storing the macro blocks of a current image and macro blocks that correspond to a search region of a previous image. The hierarchical search also requires an image storing memory for the full search, even though the amount of calculation is significantly reduced. Thus, the hardware required for performing a conventional motion estimation algorithm includes a large image storing memory for only a motion estimator, thereby increasing the size of a chip.
To solve the above problem, it is an object of the present invention to provide an apparatus for storing only the size of an image block in an upper layer, instead of the entire frame, and supplying optimal data, for a motion estimator, and a method thereof.
To achieve the above objective, the present invention provides a data supplying apparatus including an arbiter for arbitrating the use of a memory, an SDRAM for storing the image data of current and previous frames, an SRAM for storing the macro block image data of the current and previous frames, and a motion estimator for generating a motion vector and a sum of absolute difference (SAD). In particular, the data supplying apparatus comprises an SDRAM address generator for reading the image data of the current and previous frames stored in the SDRAM, in units of macro blocks, and storing the read image data in the SRAM, and writing a motion vector and an SAD generated in units of macro blocks from the motion estimator from the SRAM to the SDRAM; an FIFO module unit for reading the frame image data from the SDRAM in units of bursts and storing the read data in the SRAM, and transmitting the motion vector and the SAD from the SRAM to the SDRAM in units of bursts; and an SRAM address generator for reading data among the macro block image data of the current and previous frames from the SRAM according to hierarchical search levels and writing the read image data to the internal registers of the motion estimator, and writing the motion vector and the SAD from the motion estimator to the SRAM.